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Is there anything better than LiveATC to get accustomed with RT phraseology?
I would like to "train my ear" for RT communications and I tried to listen to approach of Dublin's Airport. I simply can't understand more than 50% words because of loud background whistle and poor (quiet) sound quality, although the mp3 player shows 320 kbps. Do they sound just like that in real life too?
Is there anything else with better quality than LiveATC? I would like to get accustomed with ICAO phraseology, so US airports will not suit my needs.
Thanks for taking time to reply!

US and UK airports should be using 99% of the same phraseology. You can read the FAA pilot/controller glossary if you want to know the differences but it is very few. I'd start with a lower volume airport, don't just jump into major hubs. Pilots use short hand and talk very fast, it isn't good for training.

@RonBeyer At the GA level it's really not 99%. I've had to actively try and avoid USA RT while training because the differences while relatively small are quite confusing as a newbie.

@RonBeyer Dan is right, especially the VFR phraseology (but not only) is really different in europe and the US. If we just take the IFR clearance into consideration the differences are huge

What does "RT" stand for?

@Steve Kuo: Radio Telephony

So, is there any other source except for LiveATC and personal receiver   to practice real world RT?

@superjet100 you don't need an expensive air band certified receiver, just a cheap SDR dongle. Search for RTL-SDR, if you want to listen to more than one channel at a time, you'll need once for each frequency, but you can hook them all to the same antenna because they are receive only.

The loud whistling and popping has to do with the equipment that the person monitoring the frequency is using in addition to the range they are from the airport.
Depending on local law you could purchase a receiver capable of receiving those frequencies yourself directly. Under some conditions however transmissions may sound like that because they are AM and subject to whatever interference is on the air at the time.
When you are in an aircraft you are subject to less interference because there are no objects between you and the transmitter. The frequencies  you need to be able to receive are 118.000 Mhz to 136.975 Mhz AM mode for civil aviation.
Even if you are not directly near a major airport there is likely controlled airspace near you that you can check by looking at a sectional for your area. That will have the frequencies in use by your local airports. Then you can listen to controllers with your local accent. Once you know the words you'll be able to pick them out of the LiveATC feed better.

Depending on local law for example: I understand that monitoring of aviation band radio in the UK is generally illegal. Additionally, 108.000-117.975 MHz are generally reserved for navigation signals, and will have very little voice transmission. 118.000 to 136.975 MHz are generally used for air/ground comms.

@JonathanWalters I knew that was the band split in the US but I don't know what it is in the UK. And the UK legal was exactly what I was thinking about when I mentioned local law. Ireland however may be different. And I'm not sure about other countries in Europe so that is definitely a per country thing that needs to be checked. You are technically not free and clear to listen to everything in the United States either, for instance it is a felony to use a radio scanner when committing a crime.

@RowanHawkins, the band is split the same way everywhere. The COMM radios can only tune 118.000 to 136.975 and the NAV/ILS radios can only tune 108.00 to 117.95.

One big difference between US and standard IACO terminology is how to declare an emergency. Pan pan pan vs mayday mayday.

@RowanHawkins Both the distress call (3 x PAN PAN) and the emergency call (3 x MAYDAY) exist in both countries. They do NOT mean the same, PAN PAN just states that you experience problems which do not bring aircraft and people on board in immediate danger (could also be a car accident which you observe below you). MAYDAY states that your aicraft and/or crew are in danger and immediate assitance is required.

@pcfreakxx minor point, ICAO is not a country.

@tedioustortoise wdym?

@pcfreakxx the post you were responding too said the "one big difference between US and standard ICAO." You responded to this by saying, "...exist in both countries."  ICAO is not a country, rather an agency of the United Nations, with 193 member states.

@tedioustortoise That’s irrelevant, because I was obviously relating to the US and the UK here - read the context!

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Can you recommend IFR material for Europe?
Is there a European equivalent to the FAA's "Instrument Flying Handbook" and "Instrument Procedures Handbook" that will illustrate how to fly different procedures in accordance with ICAO PANS-OPS Doc 8168 and read approach plates (Jeppesen), etc.?

source: Stack Exchange

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sort: votes


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What is "50 ft obstacle climbing speed"?
Vy and Vx make sense to me. They are used for fastest height gain at a given time and biggest angle of climb. But what is the purpose of that speed (it's from DA20 POH)? It's only 3 kts faster than Vx.
thanks!

In the absence of POH guidance normally Vx is the target airspeed for a 50ft obstacle. However, when the 50ft speed is included in the POH, as it is in modern aircraft, it is based upon empirical data from flight tests.  Essentially, the test pilot flies the plane searching for the best technique to offer the best performance. When that is determined, the procedure and speeds are worked into the POH, usually in procedures and tables of speeds, but sometimes in graphs.
There is allot of engineering and test department spin on the procedures, and sometimes a pilot may get better performance using a slightly different procedure and / or speed, than published.
Also, published speeds may have a buffer in them to avoid significant performance loss, if for example a maneuver puts one close to a point where sink might be higher if the pilot's airspeed control is slightly off.
So to summarize, different manufacturers have different methods of determining what their recommended procedures and speeds are.  Sometimes there are buffers built in for speeds, and sometimes not.  Sometimes a skilled pilot can outperform the recommended POH procedure.  That doesn't happen often, because POH figures are competitive and are used to sell planes.
Side story: I was evaluating a PC-12 and C-208 as platforms for scientific instruments, and flew each one with a sales man.  The PC-12 came back with a factory test pilot to fly with me.  I wanted to fly at speeds between 61 and 64k, in the Caravan, at 500 ft AGL, and 67 to 70k in the PC-12.  The Cessna Caravan would do it comfortably all day long.  Neither the salesman nor the factory test pilot was willing to fly (or let me fly) the PC-12 at those speeds at that altitude.  I did with the PC-12 at 3500 ft AGL, and it simply didn't have the stability that the Caravan did at the lower envelope.
So the same numbers in a different plane can result in very different flight characteristics.  Vx in one aircraft could be less stable in one aircraft, but Vx+3 might be much more stable.

I am inclined to believe that is a misprint from either an earlier POH or a non-OEM approved flight manual.  Here's an excerpt from the current OEM-approved DA-20 POH for the normal operating procedures.

There is an additional supplement to this for the takeoff procedures.

Note here, the figure listed for the short field takeoff climb speed of 58KIAS refers to a best rate of climb using takeoff flaps whereas Vx of 60KIAS in the manual is the best rate of climb in a cruise configuration (flaps up).
The screenshot you posted seems to indicate a climb speed for a standard takeoff as oppos d to using a short field procedure.  However the OEM manual doesn't seem to list anything like that for takeoff roll and obstacle clearing distances.

Unless your flight manual indicates some kind of performance chart which makes use of that operational speed, I don't know quite what it's used for.
As always, this data presented here is for informational purposes only; always use the manufacturer approved flight manual, supplemental data and approved cockpit placards specific to the airplane you are operating.

Its official poh from diamond website: http://www.diamondaircraft.com/wp-content/uploads/2016/01/DA202-Rev-18.pdf
I just can't understand the purpose of this speed. I can use Vx and I will be well over any obstacles ahead. Maybe this speed is used as some kind of benchmark for calculation of ground roll & takeoff distance that will place me exactly at 50ft height over end of a runway? If so, can anybody confirm this? thanks!

pics: 1) https://ibb.co/gY3znF
2) https://ibb.co/cQNs7F

This speed (60 kts) is also should to be maintained during engine failure after takeoff: https://ibb.co/k4dFSF


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Why do most commercial aircraft have their fuselage over the wing, instead of under?
Almost all commercial jets today seem to have the fuselage/cabin mounted above the wing, why is this? why isn't it mounted under the wing like some freight airplanes?
Examples of above and under?

The related post, What are the pros and cons of high-wing compared to low-wing design?, does not address the passenger airliner related aspects.

I am nominating this question to be reopened because the supposed duplicate asks about high wing military aircraft, and the answers do not substantively address this question.

Large commercial aircraft have low wings to stow away their long landing gears. Long gears make it possible to stretch the fuselage and still be able to rotate during take-off. Stretching makes it possible to tailor one basic design to a wide range of sizes, lowering the price of a single aircraft.
Large high-wing aircraft with their low fuselage position are easier to load and unload, at the price that the fuselage taper has to start shortly aft of the landing gear, so no stretching is possible. The military doesn't mind and prefers the high-wing variety. That Lockheed likes to stretch their transports (C-130, C-141) anyway is the exception that proves the rule.
Only turboprop-powered civilian aircraft may have a high wing, so there is more space for the propellers and the landing gear can be made short and light. Still, both versions exist. And the ones where the engineers did not know how to attach a jet close to the wing.
Aerodynamically a mid-wing position would be best. This is used when the payload is compact and needs little space, or is hung externally. In bombers, in other words.
In terms of stability and control both configurations are equivalent.

"Only turboprop-powered civilian aircraft may have a high wing" That's not quite true: BAe 146.

@DavidRicherby: Yes, the exception that proves the rule. Now I need to add another dreaded weasel word.

https://www.aircraftintel.com/article/view/high_wing_vs_low_wing_airplanes
Some Considerations:

High wing: easier loading
Low wing: structurally simpler
High Wing: Engines are farther from potential debris
Low Wing: Can have shorter landing gear (contra: B-24)

https://upload.wikimedia.org/wikipedia/commons/thumb/a/a3/Eurowings_bae146-300_d-aqua_arp.jpg/1920px-Eurowings_bae146-300_d-aqua_arp.jpg
https://commons.wikimedia.org/wiki/B-52_Stratofortress#/media/File:Boeing_NB-52A_with_X-15_No.1(SN_56-6670)_061219-F-1234S-001.jpg
I have to disagree with the stretching disadvantage to high wings:
https://upload.wikimedia.org/wikipedia/commons/thumb/e/e6/C-141A_C-141B_comparison.JPEG/1920px-C-141A_C-141B_comparison.JPEG

Could you edit your answer so it's not (primarily) a bunch of naked URLs?

If this @#$@# should have let me do so (instead of saying invalid file format—JPEG), I would have to begin with.

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Why are AMRAAMs often mounted on the F-16's wingtip hardpoints?
If an F-16 is armed with AMRAAM and Sidewinder missiles, with regards to inertia and roll-rate, it would seem to make sense to mount the heavier AMRAAM closer to the fuselage, and the Sidewinder's IR sensor would have a smaller blind spot (created by the aircraft's fuselage) if the weapon were mounted farther away from the fuselage.
Why are AMRAAMs often mounted on the wingtip hardpoints (e.g. as in this picture), instead of the lighter and line-of-sight dependent Sidewinders?

I'm having trouble finding anything more authoritative than a forum post on this, so leaving a comment instead of an anser, but I've been told many times that having the heavier AMRAAMs on the wingtips reduces wing flutter:  as the wings generate more lift, they tend to flex upward (and then rebound and vibrate), and wingtip weight counteracts that.

The AIM-120 weighs in at about 335lb (152kg), and the AIM-9 at about 190lb (85kg). While heavier, the Stores Management System (SMS) and the Fire Control Computer (FCC) know what is installed where, and compensate/adjust flight characteristics as needed.
You put the most capable missile, the AIM-120, out the outboard stations. You'd use that first. Only later might you want to use the shorter range AIM-9.
So, if you were to shoot the AIM-120 from Sta 2 (left inboard), you'd still have the AIM-9 out on the wingtip.
Do it the other way around.
Also, the AIM-9 since the AIM-9G can slave the missile seeker head to the aircraft radar. Target acquisition is not solely dependent on the IR in the missile and line of sight.

The AIM-9G was the first version to include SEAM (Sidewinder Expanded Acquisition Mode), basically an improved AIM-9D seeker head, but was quickly made obsolete by the AIM-9H. The latter was the first model to offer limited all-weather capability, as well as solid-state electronics and double-delta control surfaces resulting in a superior maneuverability compared to older models. SEAM slaves the seeker head of the missile to the radar when in "dogfight" mode, which enables the seeker head to be uncaged, slewed toward a specific target by the aircraft radar, and made to track that particular target before being launched.

(from F-16.net - http://www.f-16.net/f-16_armament_article1.html)

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What is the disadvantage of twin-engine fighter jets?
Some air forces in the world do not use twin-engine jets at all. For instance, Pakistan. Even though Pakistan could import twin-engine jets from China at a very cheap price, they never did that.
What is the basic disadvantage of twin-engine fighter jets over single-engine ones?
Do they cost more because of maintenance?

Which planes a country decides to buy depends on their specific needs and budget. It is not as simple as "one plane is better than another"

First of all it's a lot safer when one engine fails if you have two. Also since the availability of engine thrust is few and far apart, sometimes one big engine isn't enough and you have to use two smaller ones.

Also I'm not sure what twin engine fighter China has to offer at the moment. J-8 and JH-7 are pretty awful fighters. J-6 was OK at the time and was (still is?) in PAF service. J-11 and FC-31 are too expensive for PAF's budget. The only viable option is Hongdu L-15 trainer? The thing is, China only have engines at one thrust class, so PLAAF only have either twin engine heavyweight or single engine middleweight in service. There's no twin engine middleweight in PLAAF service like mig -29 and f/a-18 simply because there's no Chinese domestic engines of this class.

Maintenance cost. Two engines mean twice as much work in engine overhauls, but the difference to single engine airplanes gets smaller as fighters get stuffed with electronics more and more.

Twice as many engines means twice as many failures.

@MikeBrockington actually more than twice as many, because a single engine has more redundant parts built-in which are not added to each engine in a twin. But the consequences of failure are much less severe for twins.


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India issues NOTAM for Very Long range Ballistic Missile Test

India issues NOTAM for Very Long range Ballistic Missile Test

I have two questions in this regard:

Why does India need such a long and huge area?
Did China ever do this?

If not, why does India need this?

what is the relevance of China's behaviour? how are these questions Aviation.SE-related?

I agree, there is no relevance of this NOTAM to what China does or doesnt. Especially not for aviation.se. Any answer to this part of the question would be speculation.

"Why does India need such a long and huge area?" Might want to revisit the definition of "ballistic missile" :)

It's in that time window as of writing of this comment, and according to Flightradar24, there are literally planes flying through that region as if they couldn't care less.

As for why India needs such a large and wide area, they are launching a missile, and what goes up is going to come down somewhere in that area. They have a wide area in case missile goes off course. It's good practice for a nation to warn people of potential dangers in the air from rocket testing.


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Why did South Africa retire its Atlas Cheetahs?
South Africa sold its Atlas Cheetahs to Equador and bought JAS39 Gripen from Sweden.
What was the reason for retiring those Cheetahs when a lot of nations are still using Mirage-3s and 5s?
South Africa has the capability to upgrade/build/rebuild its jets by itself.
So, why retire?

Nations using Mirage 3 s and 5s are not in the same tier as SA. Cheetahs became increasingly obsolete in comparison to international fighter aircraft. Saleable to lower-tier countries or for use as in "aggressor" training, like the old Hawker Hunters they use in USA.

Argentina retired Gloster Meteors in 1970.

The Cheetah was itself an upgrade of the Mirage 3's, a 1960's aircraft, that they already had, so you can imagine how obsolete they had become by the time they were retired. SA most likely retired them because the cost of maintenance was becoming prohibitive, parts were becoming impossible to find, and yet another upgrade made no sense.

This might be on topic in [politics.se] as well.

Because airframes become obsolete.


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Why was US-made Reaper drone downed but not Byraktar TB2?
Russian Su-27s used fuel dumping techniques on US-made MQ-9 Reaper (YouTube) and Turkish Byraktar TB2 (YouTube).
MQ-9 Reaper plunged into the Black Sea, but TB2 didn't.
Why was that?

Because the Russian aircraft had a mid air collision with the MQ9 drone and not the Turkish one.

I don't think so.

@user366312 - That is exactly what happened. Why do you think otherwise?

The video shows no collision.

The propeller blade didn't bend itself. The answers in this topic outline why you do not see the instant of impact. https://aviation.stackexchange.com/questions/98162/why-is-there-no-video-of-the-drone-propellor-strike-by-russia

The general feeling of analysts is that despite the Russians' bravado on the subject, there is other stuff going on behind the curtain.  First, Russian aviation knows that the unintended collision with the Reaper was an embarrassment to the service, and doesn't care to repeat it, so they are being more cautious. Second, analysts are right - you never know what can happen in a collision like that, you can just as easily "own goal" and kill your own plane too.  They were also mindful of the geopolitical implications, so were probably trying to turn it down a notch.
Anyway, it is the view of the analysts I read that in the course of the intercept, they never looked at the insignia.  Otherwise they would've just splashed it with guns.


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Which are the advantages of low pressure levels during flight? (i.e during cruise flight in a commercial aircraft)
I understand that due to health and security reasons, there must be a minimum in the pressure inside the cabin (75 kPa). But in class I have been told that maintaining low pressure levels has advantages, which ones?

Related: "Cabin pressure is limited to 8000ft maximum, due to structural fuselage meeting (otherwise it would "explode" as a balloon)" from How does the cabin pressure controller work in a large commercial airliner?. This is to keep the pressure difference between outside (lower as altitude increases) and inside as low as acceptable, to prevent using a stronger but heavier fuselage.

You want the lowest pressure that can be tolerated by most of the population for the purpose of maintaining adequate blood oxygen levels, which is generally considered to be 8000 ft above sea level. At 8000 ft, someone with degraded lung function, like a smoker, is effectively at 10000 ft plus and is already at the threshold of having marginal blood oxygen for peak brain function.
At 40000 ft this requires a pressure differential of a little over 8 psi between the interior and exterior and you build the pressure hull to that and no more (it's a certification requirement).  As per min's comment this is partly to keep from having to make the pressure hull any stronger than it needs to be (every pound over the minimum is non-revenue ballast) and also to minimize engine bleed demand, which can be thought of as lost energy being used to keep the balloon of the pressure hull inflated instead of making thrust.  So, bottom line is it would be better for the airplane, both structurally and from an energy use standpoint, to operate with lower pressure differential and higher cabin altitude, but now the crew would have to start using supplemental oxygen and more people in the back would be getting sick.
The 787, because of its carbon fuselage, is able to go with a higher differential structurally, and its electric-pump pressurization system is a bit more efficient than taking bleed air directly, so Boeing had the option to certify to a higher differential pressure, 9 psi, which gives a 6000 ft cabin at service ceiling.  They could have used 8 psi and just shaved off more weight and used slightly lighter air pumps, but instead they increased the differential.  This was done mostly as a cabin comfort sales feature and was thought of as a bigger sales benefit than going with the weight saving route.

When transporting animals, particularly larger (zoo, show) animals, it is often requested by the handler/vet to have higher pressure altitudes.  This helps calm the animal, and makes them less active.
In contrast, for long medvac flights, it was company practice to keep the cabin pressure altitude as low as possible, unless the medical personnel requested otherwise. There is of course supplemental O2 for patients at all times.

A friend, reading this, reminded me of a flight we had, with his daughter on board, who is very allergic to bee stings.  We were in his P210, and almost at altitude.  I turned on the O2, we put on masks, and depressurized the cabin.  Within minutes, the bee was stationary, and was dispatched.  Then the cabin was re-pressurized, with no bee threat.


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Is there a type of instrument/display that guides pilots along a certain path?
What do you call an instrument that can help a pilot fly along a predetermined flight path (e.g. path thru GPS coordinates), showing them when they stray a little so they can correct? Not a control system, but just a visual feedback display. I want to say I've seen something like it before, that had two panels each with a plane symbol and "reticle", but I would like to know what it is that I'm describing. Thanks

If you talk about the display it may be the Navigation Display. The system calculating the legs between waypoints may be the FMS (Flight Manager System). All of that is independent of the Autopilot in a sense that Autopilot is using the information from FMS in some planes but both of them may live without the other.

Are you perhaps thinking of the flight director? That's a component of the visual display, but it works in connection with the FMS and other navigation systems to know what the predetermined flight path is.

What you are describing is a Course Deviation Indicator or CDI.

These are fairly standard across most aircraft however they may also be combined with a heading indicator resulting in an Horizontal Situation Indicator. There are also variants that have an aircraft symbol such as you describe.
Depending on how your aircraft is setup these units can be referenced off a radio beacon such as a VOR an ILS system for approaches or a programed GPS route.
This video covers some basic operation if you are curious.
A lot of GPS units with moving maps are generally able to display the info you describe as well.

There are even various apps that allow you to display such info on your tablet or smart phone


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How difficult is it to design a high bypass turbofan given a military derived core?
Suppose one of the big-threes is given a military low-bypass turbofan core, how difficult would it be to produce a design centered around this core that matches the competitive performance of a similar brand-new design? What parts are new aside from the fan? Does it need a new LP compressor and LP turbine? Can you safely crank up the overall pressure ratio, confident in the fact that the original design's tolerance for supersonic flight would mean the HP compressor has the ability to take the heat of higher compression subsonic flight and hence needs no modification at all?

My spidey sense tells me that you'd end up with a Frankenfan monstrosity that is not particularly optimized or efficient. If it was practical someone would've done it by now.


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Why some WWII fighters still have fabric/wood control surfaces?
I've heard people say that the reason US in WWII preferred designs with fabric control surfaces with either a metal or plywood frame is they can sustain some small arms fire without disintegrating. Is this really the reason? Or is it simply weight saving?

You may find the story of the British Mosquito interesting although it was timber skinned. The video is complete with pipe-smoking, tweed jacketed boffins, pointless music, and good old-fashioned English commentary. Apparently a senior German commented that the British had created a plane that could be built in parts in every piano workshop in the country!

@Transistor, making it in carpenter shops was kinda the point. All metal was already used for weapons production, and all metal workers were already busy making them, so using wood—and it was not just skin, it was all-wooden construction—allowed to use additional material and workforce that wouldn't be taken from production of any other weapon.

Yes tactically and strategically for the British the Mosquito among other organic-skinned aircraft were really feats of engineering that made the best of what they had to work with. However, if I was going to send my pilots off to fight for our country, I'd go metal regardless of the time period.

It was done to achieve the most flutter resistant surface for the least weight.  To prevent flutter you balance the surface to put the C of G of the surface at or ahead of the hinge line so it can't oscillate in sympathy with the wing, which adds energy back into the wing's oscillations until it all falls apart. To do this you add weights forward of the hinge somewhere.  (Hold a piece of plywood by the edge in your hand and wave your hand back and forth.  The surface wants to "trail" behind your hand movement because it's center of gravity is away from where you're holding it.  If you were able to hold the piece near the middle at its center of mass, it won't do that).
A metal skinned surface is heavier than a fabric one, and therefore requires a heavier mass balance, so the overall weight gain is substantial because adding weight aft of the hinge requires a balancing increase in front of the hinge.  But later on as the speed got up there, the fabric covering itself became a problem and designers just went with metal and lived with the higher weight.

A metal control surface can also sustain some small arms fire without disintegrating -- aircraft with metal rudders and elevators used to routinely come home with bullet holes in those surfaces.
The real reasons wood and fabric surfaces might have been preferred (though they weren't always; several designs had all-metal control surfaces) are the classic reasons for everything in aviation: cost and weight.  In the late 1930s, when many of the aircraft used in WWII were designed, it was still possible to make a wood and fabric structure, especially a control surface (as opposed to a wing), that would give the needed performance and strength and come in lighter than an all metal one, and frequently at lower cost in volume manufacturing.
As performance specifications continually crept up (higher speed, higher loading, more vibration from a larger engine, etc.), metal surfaces gained the advantage.  They could ultimately be stronger than wood and fabric, hold their surface shape over a broader speed and pressure envelope, and as noted, wouldn't disintegrate if they took a few bullets -- in fact, they were usually more durable than wood and fabric, because metal is less prone to tears and splintering.

Fabric covered control surfaces on otherwise all metal aircraft were rarely wood, but rather metal, and it was done to reduce weight, which is particularly important when it comes to the control surfaces, as heavier control surfaces translate into heavier stick movements.
Here is the rudder from a Harvard I trainer, which was fairly typical for any control surface - the ribs are stamped aluminium sheet, and the structure was riveted together, and then covered in fabric which is sewn to the ribs.
Earlier types often used steel tubing, but that had become fairly rare on military aircraft in WW2, aside from some smaller trainers.

@MeatballPrincess welcome to Aviation StackExchange, and interesting question. I don't feel the answers so far are completely inclusive of all the factors, so I'll include my interpretation of the answer. Firstly, some other variables you could keep in mind was the US's manufacturing capability during WW2 compared to countries that fielded many wood-skinned aircraft, such as the RAF. I'm not completely sure where you got your information that the US preferred wood and fabric over metal during WW2, as we had few shortages of metal and as I will explain, the performance and application of these fighters simply negated any real reason to use anything but. However, metal is expensive, and the UK's situation was too urgent to take the money and time to develop newer metal skinned prototypes. If I recall correctly balsa wood was the main skin and chemically treated stressed fabric was the most common fabric used in aircraft skinning. Of course, planes such as the Spitfire and others are exceptions, but we see fabric and metal making up a large portion of the skin on the most numerous and resource intensive applications i.e. the Hurricane and especially the Mosquito.
To address your point on durability under small arms fire, you could probably use common sense to identify the fire hazard of wood, but again it was treated to be fire-resistant (obviously) and the two materials (aluminum vs wood) have various pros and cons. As a skin, these materials just cover the frame and slightly protect the interior, of which the more vital component will be further shielded with steel plating. When bullets or cannon shells blow holes in the skin, metals such as duralumin retain some measure of rigidity and unless those shells were loaded with some seriously hot chemicals, won't burn. Wood and fabric on the other hand can be easily set off by competent incendiary rounds and will continue to burn away the aircraft's aeronautical properties. The metal used by the US was mainly duralumin, which was an aluminum-copper-magnesium alloy with a density of 2.78 g/cm^3, compared to balsa wood which is 0.16 g/cm^3. Obviously, wood and fabric (which is even less dense) are lighter than metal. However, duralumin is simply just better for fighter aircraft, or any machine with combat application. It resists crumpling and wrinkling (a huge issue for fighter planes back then) to hundreds of miles per hour greater than fabric ever will, and wood has issues two-fold: it can't be easily used in naval theaters as water rots even treated wood faster than it rusts metal, and it burns. As a result we see that the US had pretty much 0 non-metal frame and skin fighters, bombers, or reconnaisance aircraft stationed on aircraft carriers or anywhere for that matter. John K already answered the aerodynamic reasons for choosing metal, but I don't think any of the other answers explains why the US actually didn't use wood. It was duralumin for almost all of their fighters from the onset of war to today. Simple as that.

Primarily weight and manufacturing simplicity.  The fabric covered structures worked well for those applications and could be manufactured at a minimum of cost and complexity.  It had nothing to do with protection against enemy fire - most all metal aircraft are thin skinned and vulnerable to even small arms fire.


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How is crankcase ventilation handled in R-2800?
I just finished R-2800: P&W's Dependable Masterpiece and noticed there's no mention of a pump for crankcase ventilation. Is this handled by the oil scavenge pumps?

By ventilation do you actually mean return of oil?  When I see that word I think of a crankcase breather to let gasses out.  If you mean oil, it will certainly have a scavenge pump or pumps, as with any dry sump engine.

@JohnK no I'm speaking from life experience. In car engines, there's always such a pump because combustion gas would go over the piston rings and accumulate in crankcase if not constantly sucked off. It's usually a positive displacement type of pump.

The radials were virtually all dry sump systems. Within a dry sump system is an air-oil separator as well as overboard breathers for the crankcase and dry sump oil tank.

In a car the combustion gasses that blow past the piston rings are sucked out by a line connecting the crackcase to the intake manifold by a check valve (the PCV valve).  The suction "pump" is from the low pressure in the intake manifold.  Cars before the PCV valve (developed in the 50s) just vented the crankcase gasses overboard through a hose.  Aircraft engines, including the big radials and the Lycoming engine on my own plane, do the same.
Positive crankcase ventilation was probably the first pollution control device developed for cars.  Piston aircraft engines have never used pollution control devices.  They still use gasoline with lead in it.

PCV not PVC, I think.

LOL yes.  I was shopping for PVC pipe yesterday...


text:
What is the difference between a guided rocket and a guided missile?

Pakistan’s ‘Flat Trajectory’ Fatah-II Missile A Formidable Threat To India’s S-400 Missile System- Experts

According to this news article, Pakistan's Fatah-II is a guided rocket artillery.
What is the difference between a guided rocket and a guided missile?

A rocket propelled guided missile?

Various answers not withstanding, I'd suggest that in the modern military context, all missiles are rockets, specifically guided rockets, but not all rockets are missiles. Sure the word missile has other definitions as well, but not in the modern military context. Guess air-breathing cruise missiles are a special case though- conceptually they have evolved from rocket-powered missiles hence the retained terminology? It's really not 100% cut-and-dried. The word "rocket" used alone, as opposed to "rocket-powered", tends to imply that there is no guidance, but consider "moon rocket", "V-2 rocket"

In this particular context, the article describes Fatah II as a "guided multi-launch rocket system", or guided MLRS.
The military term for guided rockets is "missile". But there's also an established military term "MLRS" for Katyusha-style salvo launchers. Technically, this should be called a "multiple missile launcher", but that just isn't a common term. So they call it a Guided MLRS, to show it's a MLRS in style with guided missiles as projectiles.
A guided rocket is a missile.

But, there is also a term guided Missile. no?

@user366312 It's the original term, since a medieval missile could be an arrow or a slingshot. But no military uses them today, so the "guided" part got dropped eventually.

But, how would you describe the difference between a ballistic missile ( not maneuverable) and a cruise missile ( maneuverable) then?

@user366312 Most ballistic missiles are inertially guided. But ballistic-trajectory unguided rockets can also be called ballistic missiles... Military lingo is, basically, more about convention than it is about accuracy.

In short

What is the difference between a guided rocket and a guided missile?

A missile is the association of a flying vehicle and a weaponized payload (warhead). The vehicle is guided at all stages of its flight. There are two missile families:

The cruise missile operating at low altitude, sometimes close to the ground, is constantly propelled. Its range is limited by the fuel tank capacity. It's the counterpart in air of the underwater torpedo.

The ballistic missile is propelled for the ascent (boost phase) and returns to the ground in free fall following a parabolic trajectory. This free fall can extend the range of the vehicle. According to the range, a ballistic missile is referred to as CRBM (close range), SRBM (short range), MRBM (medium range), IRBM (intermediate range) or ICBM (intercontinental). Fathah II is a SRBM, a SRBM flies in the atmosphere. An ICBM climbs to space and a portion of its trajectory is a sub-orbital spaceflight.

A rocket is a flying vehicle propelled by a rocket-engine. This vehicle may carry a warhead or a peaceful load. It can be guided or not. The rocket-propelled grenade is an example of non-guided rocket and the Space Launch System carrying the Orion spacecraft is a civil multistage guided rocket.

A rocket engine doesn't rely on atmosphere oxygen to burn its fuel. The oxidizer is taken on-board. The fuel and the oxidizer can be solid or liquid. Rocket engines are more powerful than air-breathing engines, but they cannot deliver this power for a long time. They are used for ballistic missiles, the short boost phase ensuring a high altitude and a high velocity allowing a long unpowered ballistic trajectory.

Fattah II is a guided rocket artillery piece, a rocket-powered ballistic missile launched using a multiple launcher rocket system, with an assumed range of 400 km. It is propelled during its ascent by a single-stage solid rocket.
The wording used for missiles is somehow arbitrary and dated, in particular for guidance and propulsion, there are many variants and combinations of variants. For more, see Ballistic Missile Taxonomy.

Details
There are two different concepts in your question: Guidance and propulsion.
Guidance
The guidance system actuates control surfaces or deflects the engine nozzle to change the direction of motion, based on the knowledge of the target coordinates, and the current position.
The current position can be determined using a satellite navigation system (GNSS), but GNSS are susceptible to jamming in conflict areas. Thus an autonomous system is used, an inertial navigation system. Its accuracy degrades with time (cumulative drift), it must be realigned from time to time with a known GNSS position.
Conversely a GNSS position validity can be confirmed by comparing with the inertial system position, and spoofing can be detected.
Propulsion/guidance combinations
The simple combinations of propulsion/guidance are:

Rocket engine + no guidance: An unguided rocket carrying an explosive at relatively short distance, this is what is meant by rocket when referring to an ammunition. A short for rocket-propelled grenade.

No propulsion + guidance is called a guided bomb. A bomb is an explosive load dropped in altitude, which trajectory is determined by the launcher speed and gravity (ballistic path). Most bombs can be converted to guided bombs by adding a guidance kit, e.g. the US JDAM. Relatively short range.

Other combinations leverage guidance:

Air-breathing + guidance: A missile propelled by an air-breathing engine, often a turbojet like in the Storm Shadow. It's called a cruise missile. This missile is constantly powered.

Rocket engines + guidance: A long-range guided rocket carrying a warhead, called a ballistic missile. This missile is powered only for its ascent. An ICBM has a sub-orbital trajectory portion, the engine is used again for re-entry. After the apogee, the trajectory is ballistic.

I Don't get how a ballistic missile can be said to be guided.

@user366312 almost all 'Ballistic' missiles are steered during the powered ascent before ballistic flight begins, as otherwise your accuracy is just 'can hit the right timezone'. Some also stretch the definition by having mid course gas jets or terminal phase aerodynamic control as well. We probably should have a better names for the various flavors of Ballistic missile, but I suspect the secrecy around them means nobody wants to talk details that would make classification meaningful.

Generally, in the military world:

Missile - Powered, guided
Rocket - Powered, unguided
Dumb bomb - Unpowered, unguided
Smart Bomb - Unpowered, guided

News outlets frequently mix it up.

Rockets do not have air breathing engines.  If it is powered, unguided, and takes air into its engines, then I guess you might call it a target drone.

@AnonymousPhysicist - Air breathing has little do do with it. Guidance, or lack of, is the key.

A guided rocket-powered missile is, technically, a guided rocket. But that's not how the term is used in the military.

A ballistic missile is unguided, a cruise missile is guided.

A rocket denotes a method of propulsion, I.e. a reaction thrust device where both fuel and oxidiser are carried on board.  In common usage, a device powered by a rocket engine is often called a rocket.  A missile is a device intended to hit a specific target, this may be propelled by any means - sometimes a rocket.

Merrian Webster’s Dictionary defines a rocket as:
a: a firework consisting of a case partly filled with a combustible composition fastened to a guiding stick and propelled through the air by the rearward discharge of the gases liberated by combustion
b: a similar device used as an incendiary weapon or as a propelling unit (as for a lifesaving line)
Similarly, a missile is defined as:
an object (such as a weapon) thrown or projected usually so as to strike something at a distance.
It further goes on to define a guided missile as:
a missile whose course may be altered during flight (as by a target-seeking radar device).
For all practical purposes, a guided rocket and a guided missile are one of the same.  It refers to any number of different types of projectile weapons, generally consisting of a rocket motor to propel them, an explosive or otherwise incendiary warhead and some type of guidance system Allowing for either direct command guidance of the weapon to the target by the shooter or autonomous guidance.
The term rocket is generally used with a smaller unguided projectile weapon system which uses a rocket engine for propulsion i.e. artillery rockets, aerial rockets, etc.  this nomenclature is not always honored (e.g. a Zuni missile is an unguided weapon, an M26 GMLRS, etc).  Missiles in modern warfare quite often denote a larger projectile weapon as described above with a warhead and guidance system for them, but, again, not always the case i.e. a ballistic missile, etc.


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What problem led India to purchase Dassault Rafale?
The Su-30MKI is a contemporary, highly capable fighter aircraft. Since the 2000s, India has acquired a fleet of 260 such fighters.
What factors contributed to the Indian Air Force's assessment that these jets did not suffice for their operational needs?
What were the specific reasons behind India's procurement of 36 Dassault Rafale jets? Did practical military requirements or political considerations drive this acquisition?

Rafale is useful for putting on our carriers and for our navy

and India has a stock of Mirage 2000s, which I think they like quite a bit. And have weapons and other systems that won't fit on their Soviet designed aircraft.

Not wanting to be tied to Russia is probably also a factor

@MikeB, I'm not a diplomat or anyone qualified to speak on this and this site is not for politics but India has no issues keeping neutral relations with Russia and doesn't plan to break ties any soon.

@AadirajAnil, Rafale is useful for putting on our carriers and for our navy --- Faulty assumption! There were already 40 Mig-29Ks purchased for that purpose. According to my analysis, the purchase of Rafale is a total political decision, most probably to give jobs to BJP allies like Anil Ambani, etc. However, I am here for a deeper and more reliable analysis.

@user366312, yeah, I know. There's a whole Wikipedia article on the controversy and it's not something that hasn't been covered in the news. Put this question on reddit and you will get the wildest answers that will cover the politics part too. You know, if you wanted to get into the detailed politics and talk about Anil Ambani, this isn't the greatest place...


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What is the function of Boeing C-17 Globemaster III in the Indian Air Force?
Why does India need Boeing C-17 Globemaster IIIs?
What purpose do they serve in the Indian Military?

@DigitalDracula, the reason you can see in the edit history. Deletion of a sentence is giving this question up votes.

I find it incredibly hard to understand that the purpose of a transport aircraft would not be self-evident.

It’s a transport aircraft. It’s self-explanatory.

@Jpe61 It's not the only transport aircraft in the world.

@Jpe61, there were no Globemasters in the Indian inventory before 2009.

Question specifically asks "What is the function of Boeing C-17 Globemaster III in the Indian Air Force", not what is it's function compared to other transport aircraft in IAF inventory, or why C-17 was selected over some other acft.

The C-17 serves the same purpose in the Indian military as it does in other armed forces: it provides large-scale airlift.
India is a large country that has long borders with unfriendly neighbors, so it has a requirement to move troops and supplies quickly to any hotspots.

"The Indian military needs to do three things: augment its ability to quickly lift larger numbers of troops as it views possible threats on its border with China; strengthen its presence on the Pakistani border; and fight terrorism and low-intensity warfare", said a senior Defence Ministry official. "India needs to triple its lift capacity", said the official.

India spent on the order of $5B buying these aircraft, it's unlikely they'd pay that much for aircraft they don't need.

In addition, India has almost 7000 troops deployed worldwide on UN peacekeeping missions, these airplanes help transport and supply them.

there were no Globemasters in the Indian inventory before 2009.


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Do the design and manufacturing of cruise missile engines and aircraft jet engines require the same amount of efforts?
Cruise missile engines are relatively smaller in size. However, they might need the same level of expertise e.g. metallurgy, single-crystal blades, etc.
Do the design and manufacturing of cruise missile engines and aircraft jet engines require the same level of effort in terms of experience, infrastructure, and R&D investment?
Please, explain: Why.

It should be noted that many components, chemistries, and manufacturing techniques of aircraft jet engine components are highly-prized state secrets. Contrast with cruise missile engines which are generally expected to fall into enemy hands (albeit hopefully in pieces). To stress that point, if I'm not mistaken a US missile (air-to-air, not cruise) that failed to explode in a Chinese combat aircraft a few decades ago was the genesis of a few generations of Chinese air-to-air capability when the Chinese jet managed to land with the missile intact.

@dotancohen That was an AIM-9 launched by a RoC-AF F-86 and it plugged into a PLAAF J-5, intact. The Chinese tried to reverse engineer it but failed (of course, that was 1958) so it was transferred to Soviet Union. Then in 3 years we have a second source for AIM-9 for the other half of the world.

Yeah, I thought it was a sidewinder but had no idea it was that early. Sidewinders in 1958? With that in mind the cannonless F-4s make a bit more sense. I thought that late 1950's missiles were more primitive. In any case, the point stands that missile components are expected to fall into enemy hands (today at least) whereas jet engine components can still be protected from such, to an extent. In fact I think an F-35 is being fished out of the ocean right now for that purpose.

The service life of a cruise missile engine is a few hours at most, while airplane engines lasts 1000 hours at least. This alone makes things orders of magnitudes easier.
Also the engine accounts for less than 5% of the weight of a missile but more than 15% on a jet fighter, so less effort could be spent on weight reduction.
Additionally, for surface-launched cruise missiles, the weight budget of the missile is almost unlimited, meaning it could carry arbitrarily large amount fuel to compensate for bad fuel economy. The limiting factor for the range of the missile is more often navigation and homing, rather than fuel and fuel economy.
Finally, a cruise missile flies a at very predictable altitude and air speed and doesn't maneuver much, and always runs at full thrust. As a result, problems like compressor chocking and vibration only needs to be solved for those relatively simple working conditions.
As a matter of fact, other than some long range air-launched cruise missiles that are more constrained by weight and size (e.g. AGM-86), most cruise missiles below 300 km range are quite OK with turbojets even today.

As mentioned in the comments here, those comparisons are only between a cruise missile and military airplane. If you add civilian/commercial  (passenger) airplanes to the scene, you'll have to deal with even more complications, such as:

State of the art fuel economy
Near-zero failure rate
Tens of thousands of hours of service life
Noise
Foreign object ingestion
Arresting engine fragments, had the engine been damaged while in operation

The list goes on and on. In short, an cruise missile engine is a minimum use case, i.e to generate sufficient thrust with acceptable amount of fuel for relatively short period of time, but airplanes engines, especially commercial ones, are concerned with much beyond that.

@MichaelHall Yes, updated.

Isn't FOD just as important (if not even more) for military jet engines?

@Bergi It is important but I wouldn't say it's "as" important. Over the years birds have killed much more military pilots than airliner crew and passengers.

@Bergi FOD is relevant for military jets, but for missile engines it's less likely to be an issue. When you're designing an engine for the many thousands of hours that a passenger jet will fly, chances are it'll meet a bird eventually. A particular design of missile accrues orders of magnitude fewer flying hours, with correspondingly lower chances of bird strike. Plus, cruise missiles are fired from launchers, rather than taking off from runways. Mostly the only time they have the engine running while near enough to ground for FOD risk is a split-second before impact, at which point it's moot.

@anaximander I understand it's not an issue for missile engines. I just was surprised to see the point listed as a difference between military and civilian jet engines, not in the first part of the answer. And I wasn't even thinking of bird strikes but more of gravel on rough grass fields etc that military jets might need to operate from.

@user3528438 of course civil aviation tends to get above most birds' flight ceilings, and stay there for much of the flight, while military aircraft can spend significant amounts of time down low where there are far more (big heavy) birds.  I've often looked down on RAF jets in the Tornado days while walking in the mountains, but I've only seen civil aircraft from above at airfields (Concorde coming in to Filton was a good spot - they stopped the traffic  and if you were lucky there was a really good view from the flyover just before the threshold)

Basically, when considering engineering for munitions, the following principle applies: "it only has to last long enough to reach its target". This can produce all sorts of seemingly counterintuitive design decisions. For instance, there's a story that goes that, when designing the Javelin missile, the software leaked memory quite badly. The solution was not to fix the memory leak, but to calculate the leakage rate, and add enough memory that it would not run out before the missile hit its target.

@SebastianLenartowicz do you have a source for that anecdote?  Realise it's just illustrative, but interested: I couldn't find anything.

@2e0byo The story seems to have arisen in the mid-'90s on comp.lang.ada, but regarding an unspecified missile system rather than the Javelin. I've encountered the story multiple times over the years, and it seems I've conflated the two. This HN thread includes a link to both the original post (now backed up in Google Groups, apparently), as well as a number of other, similar tales. If you can't access the Groups link, Raymond Chen quotes the full text in his blog.

@SebastianLenartowicz thank you: that was a fascinating rabbit hole.  I guess calling detonate() is a new meaning for the phrase 'garbage collection'...

An important difference between cruise missile engines and aircraft engines is their lifecycle.
A cruise missile has to perform only a single start and a single flight of at most a few hours. It is then disposed in an almighty bang. The majority of lifecycle costs are in the engineering and production (labour + materials).
A jet engine has to perform many starts, many flight hours. It goes through many temperature cycles. It will be maintained to extend its life. The total cost of the fuel it burns is a significant part of the lifecycle cost, and so are the maintenance costs. For jet engines, additional engineering costs to improve the fuel efficiency or reduce maintenance costs give a better return on investment than for missile engines.
Based on that,I expect the jet engine to require a higher level of effort in terms of experience, infrastructure, and R&D investment.

Are cruise missile engines ever started just to make sure they still work, to make sure lubricants and other materials have not deteriorated while in storage, etc?

@tml the large Hound Dog cruise missiles once carried by the B-52 could have their engines started while on the pylon as needed "In 1960 SAC developed a method for using the missiles' jet engines to provide extra power for the B-52 carrier in flight or on takeoff. The missiles could then be refueled in flight from the bomber's fuel tanks. " https://web.archive.org/web/20071115211713/http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=383

Not even the same order of magnitude.
The development costs for engines rank as follows:
Transport aviation >= Military jets >> Missiles
Some details on military engines are available in a report (admittedly an old one). It shows 100M to 1B to be spent on development per engine model. Smaller engines do cost less to develop.
For major civil engines, the cost is up to 2B.
Most military engines are relatively low-tech, compared to airliners. Their reliability, efficiency and certification requirements are very relaxed. Fewer advanced technologies are used, simpler blade cooling, sometimes lower turbine inlet temperatures. A military engine will generally require more maintenance and repairs per flight hour compared to a civil engine of the same era.
However, special performance requirements, often unrealistic initial expectations, and large government budgets lead to some major high-cost military developments as well. Every once in a while, some of them do bear fruit.
For cruise missiles, the engine is almost an off-the-shelf item. The simple reason is that the greatest cost drivers in an aerial engine are reliability and fuel efficiency.
As far as reliability, missile engines are disposable items with low performance requirements. A reliability level of less than 99% per flight is considered sufficient for them. Some cruise missiles are expected to fail to launch or fail underway. More will fail for other reasons.
While efficiency means range for the military, turbofans already offer such an overwhelming advantage over rockets and ramjets that there's no need to work on a better turbofan to extend their range any further.
Simplicity is even more important in missiles, since their engines have to spend years in storage before actually being used.

I wouldn't say military jet engines are 'lower tech'. In fact, many share the same gas generator (F101/CFM56 or D-30) or are pretty much the same (JT8D/RM8). Specifically, turbine inlet temperature is almost invariably higher in military engines (even for the same/shared turbine), exactly because they can afford shorter lifespan / higher maintenance and risk.


text:
Why hasn't there been an alternative to jet engines yet?
Why do airlines and military jet aircraft still use jet engines after 85 years of the introduction of this technology?
Why hasn't there been a viable alternative to jet engines yet, even though this technology is one of the most complex and unaffordable?

We still use wheels, after being invented thousands of years ago! Why? It is an efficient means to be able to transport something. Over the thousands of years, the wheel has improved a lot though: wood, metal, rubber to composites.
The same is applicable to jet engines, which is a very broad classification of the propulsion system of an aircraft. From Wikipedia, we read:

"the term jet engine typically refers to an internal combustion air-breathing jet engine such as a turbojet, turbofan, ramjet, pulse jet, or scramjet. In general, jet engines are internal combustion engines.

Like the wheel, the "jet engine" has evolved to an efficient propulsion system for specific applications.
We know that the propulsive efficiency increased when we accelerate more mass with little increase in velocity. In the end we try to apply the propulsion system to give us the best overall efficiency for the platform. So, for lower speed applications, a propeller (using a turboshaft engine), medium speed the high or ultra high bypass turbofan engines, for high speeds the low bypass turbofan engines and straight turbojet engines (with possibility to use reheat/afterburner) to ultra high speed applications using ramjet or scramjet propulsion systems.

Source: E. S. Abdelghany, et. al. , 2013, Effect of Bleed air on Performance of Turbofan Engines, 51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition
Based on the application the propulsion system is chosen. Note that years of development and billions of dollars are required to advance the technology. Choosing an optimum bypass ratio from what optimum preliminary design gives us may be unfeasible to develop, or the benefits may be not worth the development investments.
Dr. Epstein has created a very nice overview:

Source: Dr. A.H. Epstein, 2014, Aeropropulsion for commercial aviation in the twenty-first century and research directions needed, AIAA Journal 52(5):901-911
Know that between the lower left and upper right it has taken us propulsion engineers more than 60 years.
Currently, there are no other scalable power sources with a higher power to weight ratio than "jet engines". Why there aren't any is similar to asking why we haven't invented the antigravity machine yet.

Not only that, but the computers running these engines are still using the binary numeral system, which is 345 years old.
There are multiple viable and practically employed alternatives to jet engines:

Turboprops, which are used on nearly all commuter and many regional airliners
Piston engines, used in general aviation
Electric propulsion, useful for very short trips such as training

We might in fact be approaching the end of the jet domination era: with carbon emissions being a concern, multiple airport queues often being longer than the flight itself, and engine developers promising to solve turboprop noise issues with so-called propfans or open rotors, the 5% speed difference isn't worth the extra fuel. And electrics are so much simpler and more reliable than any other drivetrain that they might displace turboprops from GA.
For long-range airliners, jet engines are simply the best technology we currently have, on a balance of power and energy density, reliability, efficiency, and noise levels, in this order.

Also, "jet" is a very broad category. We went from jet engines to turbo jets to low bypass turbo fans to high bypass turbo fans to very high bypass turbofans to – likely pretty soon – open fans. There's ramjets and scramjets, as well as reconfigurable engines like the Olympus and the J-58.

And minor issues in alternatives to overcome, like energy density.

@JörgWMittag broad and fuzzy.  It's fairly arbitrary saying that a turbofan (which gets most of its thrust from the bypass air and some from the core) is in the same category not just as a turbojet but a ramjet while a turboprop (that gets most of its thrust from prop and some from the core) isn't.  Of course the core:bypass ratio is different, as is the gearing, but a difference in numbers of similar magnitude is a small difference compared to presence/absence of major features.


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How can a supersonic cruise missile be intercepted?

India fires missile into Pakistan after ‘technical malfunction’

The above news says that India accidentally fired a supersonic missile, most probably a BrahMos cruise missile, into Pakistan. The most probable reason would be a technical malfunction. Luckily, the missile was not carrying any warhead i.e was unarmed, and the Indian Foreign Office (FO) also apologized for the error.
However, Pakistan's social media is very upset regarding the Pakistan military's incapability to intercept this missile.
Pakistan has LY-80 and FD2000 SAM systems from China.
Are these systems capable of intercepting BrahMos like supersonic cruise missiles?
If YES, what was the possible reason for not intercepting the missile?
If NOT, which systems can?

I would suggest this may not be on topic for aviation SE, but if it is https://en.wikipedia.org/wiki/Sprint_(missile) indicates that such intercepts are possible with the application of sufficient money.

@GremlinWranger, that was against ballistic missiles, and was scrapped anyway.

The Pakistani army not being heightened state of preparedness, this is simply a case of not detecting the missile in question. Detecting one of those requires constant radar surveillance, and even that does not guarantee detection, as was seen in the case where a massive drone flew from Ukraine to Croatia, undetected, despite massive NATO surveillance.

I echo that this might not be appropriate for this forum. That said, supersonic cruise missiles have a relatively small engagement window. If the receiving party is prepared for the attack, both ground and airborne systems can usually intercept a single missile. If the sending party cues the receiving party to an accidental launch, there may also be enough time to scramble alert aircraft to do the same.

Cruise missiles are possible, but difficult to intercept.
The interception rate against cruise missiles is unknown, but generally lower than against aircraft. Take all figures as relative comparisons and all numbers as just orders of magnitude. In general, a kill probability of 50-90% is considered effective.
This paper includes some math. This is for a point target being specifically defended, against an expected attack. There are multiple factors that can break the kill chain, and you can see how 50% can quickly turn into 5% if the missile is considerably more advanced.
Speed complicates interception in several ways. It gives less time to detect, identify, prepare to fire, and engage the target. It also multiplies the effect of error in tracking and targeting. Overall, the difficulty of interception scales approximately with speed squared. The paper above is for guns, but the math for missiles works in similar ways.
As can be seen from these sources, key factors that affect missile interception difficulty include:

Speed
Maneuverability
Countermeasures
Jamming

The Brahmos missile represents the mid-upper tier of ~2010 Russian missile technology, augmented with Indian-developed software on Western hardware. It's been designed to defeat medium and large warships of modern navies, including the USN. Such ships are protected with at least 3 tiers of missile defense: SM-2 at a long range, ESSM within 30 nmi, and Phalanx CIWS at close range.
Given such targets, the Brahmos missile includes the widest range of electronic countermeasures among modern missiles, the highest speed, and is capable of various maneuvering profiles. In comparison, the Chinese systems employed in Pakistan are closely based on 1980s Soviet SAM systems.
The HQ-16 is inadequate against missiles such as Brahmos, lacking in both range and speed. The missile is outside its engagement envelope.
The FD2000 is more sophisticated, being based on a still highly sought-after system. But it's likely to only include the basic anti-aircraft tier the S-300, not the newer anti-missile tier that the market is after.
It would've been unexpected if a 2010 missile designed against warships got intercepted by a 1980s SAM on low alert. That said, every interception has a chance of success - stealth bombers have been hit and downed by outdated SAM. The difference is, the Serbs were expecting attacks in their successful F/A-117 hits, the Pakistani weren't.
As for what systems are needed to intercept such a missile, it all depends on the required kill probability. Nothing would give 100%. But to rely on a steady kill rate above 50%, one would have to employ a modern system with specialized anti-missile capability such as SM-3, MEADS, or S-400.
To bring the kill rate up further, to where 90% can be talked about, one would have to step up to Integrated Air Defense Systems - a combination of long-range radars, combat air patrols, EAW/AWACS, fighters ready to scramble, and, then, layered long-range, medium-range and short-range SAM systems. 4 to 6 separate interception events, each with an independent chance to kill the target.
The technology would also have to be state of the art, such as S-500, modern jets like the F-35, Typhoon or Su-30, with new missiles like Meteor or latest versions of R-77 or AMRAAM, plus modern local air defense systems. The fighters can be older, though, as long as they get upgraded radars.
The US can afford to protect its major cities with such measures, and would, if it perceived a risk of a cruise missile strike. Russia only protects Moscow and near-frontline cities to this extent. USN carrier strike groups are shielded against missile attack to this level.
It's also critical that these systems have their electronics upgraded to the latest versions on a regular basis, to have the upper hand in electronic warfare. So a missile shield across a lot of territory is among the most expensive defenses to maintain.
The biggest factor not mentioned above is foreknowledge. If you know you're going after a missile flying from point A to point B at time HH:MM, very high Pk above 90% can be achieved. If you're not actively looking for cruise missiles, even the best systems can be ineffective. And if it's unexpected to the point of disbelief, one can land a Cessna on the Red Square.

Very nice and insightful answer. However I would far restrain from giving absolute intercept probability numbers. I believe such numbers are almost always pure speculation. Another note: the Meteor is (to my knowledge) only in service with the Eurofighters and Rafals, so not yet available for F-35s.

@U_flow True, these rates have not been tested in a real-life wide-scale scenario. I simplified it to just talking about brackets of ~90% (high confidence), 50-90% (effective) and <50% (ineffective). And these are still just measures of expectation rather than performance.

Yes, intercepting incoming supersonic cruise missiles is possible. There are several ways:

Anti-Missile Missile: If the missile is detected early enough, you can launch an anti-missile missiles. Examples for such missile systems are the patriot system, or the one you asked about LY-80/HQ-16. A lot of these systems are designed as anti-ballistic missiles (ABM), but because of the similar task and generally lower intercept requirements (less speed, lower altitude compared to a ballistic missile), ABM systems are generally capable of intercepting a supersonic missile as well. For example the LY-80/HQ-16 can intercept targets as low as 15m above ground level. They can also be used against similar flying targets such as helicopters, aircrafts and even drones (although that might be costly). The Brahmos flies up to Mach 4 but in cruise flight most likely slower, the LY-80/HQ-16 has a similar top speed. This makes intercept more difficult e.g. you have less time to launch the intercept missile or the anti-missile system must be located in a more favourable spot.
Close-in weapons systems: If you spot the missile very late or if the missile penetrated your outer defense for example because it uses terrain masking or sea skimming tactics, you can also use Close-in weapons systems (CIWS), which are simply very rapid firing machine guns which try to hit the incoming missile at close distances (<1km). These weapons are however primarily used to defend one point in space, for example a ship or a military base.
Energy Weapons: Until now in very experimental stages are energy weapons. Because of atmospheric disturbances and other technical challenges, these are however not (yet?) used for defense against missiles. However some systems or this one against "low-end threat" are now coming into existence.

Coming back to your question: What the exact reason is, will very likely remain a secret of the pakistani army simply because this information could be exploited by an agressor, therefore the things that might have gone wrong are endless. Some of the top of my head.

The missile was not detected: Reasons might be because it successfully used sea skimming or terrain masking tactics, or because it is stelthier then anticipated, or because the intercept radar malfunctioned or because the radar operator was asleep.
Unfavourable defending position: If your defending missile is far away from the incoming missile, it has to fly for longer. Also if the incoming missile is very fast you have a shorter time to react and also you have to fly faster to consumate the intercept. Perhaps the combination of these factors was just not in favor for the Pakistanis. However normally the defender very closely analyzes where to station his forces in order to avoid exactly such a situation.
Technical problems with consuming intercept: Anti-missiles do not always hit, there is a intercept probability, this is why often several anti-missiles are started to counter one incoming threat. Perhaps the Pakistanis were just unlucky.
The intercept was deemed unnecessary: Missiles are not cheap. If it was deemed that an intercept was unnecessary, because the projected target area is uninhabitated/unimportant, then perhaps someone decided that it is just not worth the cost.
Human factor problems: This could include miscommunications, conflicting area of responsibility and so forth and so on.

Pakistani military mentioned heavy civilian air traffic, though. And, probably, they tried to avoid Ukraine International Airlines Flight 752-like incident. Is that a possibility?

Sure, that seems also like an likely explanation. Perhaps they deemed it improbable that India would attack with a singular missile, so they decided not to intercept in order not to trigger diplomatic problems. Again we will likely never know.

@U_flow it’s hard to imagine that shooting down a missile that’s entered your airspace would cause diplomatic problems.

If you are 100% sure that you are shooting a missile. My point is that perhaps they were not entirely certain what they saw. But again just a possibility from my Perspektive.

@U_flow, … if they saw it at all, or saw it for enough time to even start to think what it is – if flies low and fast.


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Can you bust the MDA/DA minima in a non-precision approach when flying the CDFA technique?
Is it true that when flying a non-precision approach flying the CDFA - Continious Descend Final Approach Technique can or shall be used. This allows to treat the MDA as a DA meaning you fly down to a DA and take the continue / go-around decision like in a precision approach, or the MAP - Missed Approach Point, whichever is earlier? In a step down non-precision approach the MDA must not be crossed below and a Missed approach must be executed no later than the MAP. So is it true that technically you will go slightly below the MDA when flying the CDFA technique as the decision is taken at that point not the actual go around meaning you could lose 50ft during that manoeuver. Is it a legal requirement to add a increment to the MDA in that case this is a debate I am having. I have not found anything in the EASA CAT or FAA FAR that require an increment to the MDA/DA when flying the CDFA technique or am I wrong? Nevertheless in the ATPL manual I read I came across the following part when flying GNSS Approaches:

Does such an increment even exist? Is it an actual procedure to add 50ft or an increment to the MDA/DA when using the CDFA technique or not? I have not found anything like this in the SOP of an airline. Technically there would have to be a table for different airplanes, because 50ft would be too generic. Is it done in FAA or EASA is there a difference maybe that I am not aware of?
Following I found in the ICAO DOC. 8168

It's not totally clear what you are asking... "Can you bust the MDA/DA minima in a non-precision approach when flying the CDFA technique?"  By "can", are you asking whether or not you are allowed to bust MDA, (by initiating a missed approach at the MDA) or whether it is possible to bust it if the approach is not planned with a derived DA/H and flown correctly?

@MichaelHall sorry for the confusion, to clarify what I am referring to is the following: Under no circumstance can you go under the MDA unles the required visual requirements are met. However when flying the CDFA technique the minima is treated as a DA meaning the decision is taken at that stage, if a MAP has to be executed, you woul technically go below. I have not found an EASA regulation that requires you to have a derived DA/H and how it is applied exactly...

I understand it quite well, and it is apparent that you do as well.  My question was rhetorical mainly, to prompt you to consider clarifying the intent in the question itself.

Jeppessen charts always include a note that the CDFA requires authorization.  So I believe the exact procedure is not published.
My SOP does include the 50 ft increment on the MDA.
How this gets implemented at other airlines probably depends on the equipment and LOA.
Reference FAA AC 120-108, particularly 6.f, et seq.

This allows to treat the MDA as a DA meaning you fly down to a DA and take the continue / go-around decision like in a precision approach, or the MAP - Missed Approach Point, whichever is earlier?

You are confusing two different things here.  Where the approach course intersects the DA, that is the MAP.  They are not in different places.  However, some chart formats, including Jeppessen, depict more than one MAP to include the LNAV procedure in the diagram.
I have a MAP study guide that may be helpful for this.
Note: There is a nuance to this in the Advisory Circular.  FAA effectively amends the CDFA missed approach procedure with, "Proceed on track to the MAP before accomplishing a turn."  This is for lateral guidance and could require extra planning in the case of "Non-RNAV NPAs" mentioned in that document.  See KDCA LDA-Z Rwy 19 for example.  My SOP does not allow CDFA for Non-RNAV NPAs so that's truly beyond my expertise.

Thanks for your response and study guide. The actual thing that I am trying to figure out is whether the increment is a legal must or only a good thing to do...

@TedStaggs The CDFA requires an LOA and the LOA requires an increment.  This is the realm of procedural standards and administrative inspectors.  It is not a decree of any legislature.

@TedStaggs I added an FAA link in my answer.  It is not going to mention 50 ft anywhere, but it does provide a rough outline for authorization.


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What is the best route to convert my easa licence and ratings to FAA equal?
I currently hold an EASA frozen ATPl, CPL, MEP, SEP, IR, CFI, APS MCC, UPRT,.... .
I converted my PPL A licence to FAA PPL with the SEP rating.
Now I wonder what the best route is to convert all the other ratings and licences in the easiest and most cost efficient way.


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What happens if you put too much oil into a reciprocating engine wet sump?
Apparently putting too much oil into your airplane engine is really bad and can be expensive but why? Will the excess oil go out via the oil breather,... ? Thank you

Same reason as car engines -   https://mechanics.stackexchange.com/questions/24679/what-actually-happens-when-there-is-way-too-much-oil-in-a-car-engine

Nothing bad happens. It just blows out all over your belly. For example, my Cessna 210 maintenance manual says to add 10 qts of oil when you do an oil change. If we do that 1/2 qt goes to the filter and 1 1/2 qts get blown overboard on the first flight. So we add 8 qts and then keep it at 6-7 quarts after the first flight.


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What causes Gusty winds? ( Meteorlogy)
I was wondering why winds can become gusty. I know that gusty winds tend to be related with frontal passage. Thanks : )

General weather questions without a specific aviation component are often a better fit on earthscience.SE.

Since you mention 'frontal passage' it is assumed that the term "air mass" is understood and also the reasons for the movement of air masses. The movement of an air mass relative to the earth's surface is what we, standing on the surface, physically feel and experience as wind.
There are things that affect the smooth flow of the air mass, such as terrain, pressure gradients, other air masses, man made obstacles etc. and these can occur at different scales. By this we mean at the continental/oceanic scale, down to the scale of human made buildings or small but significant natural outcroppings.
Localised and somewhat unpredictable short term disturbances to the smooth flow of the air mass are what we perceive as 'gusts'. Visualize it in a similar manner to the way flowing water is churned by an obstacle in its flow path and the factors that cause the churning. Try listing these factors for yourself, both for water, and for the atmospheric air.


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What is the physical difference between an airplane having let's say 150 horsepower to an airplane having 250 horsepower?
I was wondering what defines horsepower in an airplane piston engine and how can it be changed?, is horsepower changing during flight?

Horsepower is torque x RPM so it changes with throttle and RPM.
The published value is the maximum horsepower rating, and is the rating of particular engine at wide open throttle at sea level, and redline RPM, on a standard day (59F, 29.92" of mercury).
They have large cylinder volumes to produce torque at low RPMs to accommodate direct drive propellers.  Normally aspirated aircraft engines are, roughly, 1/2 HP per cubic inch, which varies somewhat depending on compression ratio. A higher compression ratio, requiring 100 octane fuel, will be a bit more than .5 hp/cu in.  For example, an 80 octane Lycoming O-320 is 150HP maximum with 320 cubic inches, or .46 hp/cu in.  The newer 100 octane O-320s have 160 hp due to a higher compression ratio and so are at .5.  A 100 octane Lyc O-360 with 360 cubic inches is 180 hp or .5 hp/cu in, and the 200 HP version is .55 hp/cu in (due to different valves plus a higher compression ratio).
So, as a rough rule of thumb, the engine's horsepower rating tells you, mainly, that the displacement in cubic inches is approximately the rating x2, give or take say, 5-10%, for a normally aspirated direct drive engine.
To get significantly above that requires reduction gearboxes to allow the engine to spin (pump air) faster and if you look at a geared engine like the Rotax 912, you are getting about double the power per displacement, or 1 HP per cu in (80 hp from 79 cu in).

Thanks a lot : )

Another related rule of thumb that can come in handy is specific fuel consumption.  If you  use the typical value of an air cooled carbureted aircraft engine of about .45 lbs/hp/hr, you can make a pretty close guess at the airplane's fuel consumption in cruise.  For a 150 hp engine at 75% power, = 112.5 hp, times .45 = 50 lbs/hr, or a bit less than 8 us gal/hr, which is pretty typical for a Cessna 172.  Fuel injected engines are slightly better, maybe .43.  Modern car engines are in the mid-high .3s, diesels low .3s.  2 strokes and turboprops are gas guzzlers, in the .5-.6 range.

Horsepower in airplane piston engine is defined as in any other piston engine. A piston engine realizes a certain moment at certain RPM. When you multiply that (actually M[Nm] * ω[s-1] = P [W] ---> P [W] * 1.341 = HP). That's why in a 150 HP engine, you don't realize 150 HP at all RPMs, only at certain RPMs (usually near max RPM).
Furthermore, if an airplane flies 300KTAS (~160m/s) at max power, 250HP (~185kW), you will get thrust:
T = P/v = 185/160 = 1.156 kN
For the same velocity, a 150 HP (~110 kW) engine will give you:
T = P/v = 110/160 = 1.156 kN = 0.687 kN
See the figure below, it's a sample that shows drag that you need to overcome with your thrust at different velocities. It's for an example 700 kg airplane at 100 m ASL (above sea level) with 150HP or 250HP engines. Of course, the 250HP one will weigh more, but I've ignored that for this example. Max throttle assumed, though you can change it during flight. One throttle (power) setting will give you max range, another will give you max endurance, while max throttle will often give you best manoeuvring performance.

Hope that answers your question. Have a nice day!

You should add that the power is also dependent on throttle position. A piston engine may run at max power rpm and still make a fraction of max power if there is no load .

Thanks a lot :)


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Why are all-moving horizontal stabilizers common but all-moving rudders rare on fighters?
According to Wikipedia

Stabilators were developed to achieve adequate pitch control in supersonic flight, and are almost universal on modern military combat aircraft. All non-delta-winged supersonic aircraft use stabilators because with conventional control surfaces, shock waves can form past the elevator hinge, causing severe Mach tuck.

If this is the case with supersonic pitch control, why use an all-moving elevator but a conventional rudder? Doesn't yaw control have the same issue? Or is it because rudders are rarely used?

The reason why you want a all moving vertical tails is you can use FBW to make it more effective hence smaller (lighter, lower drag). The reason why you don't want to do it is because it's expensive and hard to do right (e.g. reliably) and not as useful (there's no performance gain except smaller and lighter).

@user3528438 what about control when flying supersonic? Does shockwave form past the rudder hinge? I get that mack tuck doesn't matter much for rudders because they are already at the rearmost part of the aircraft and tucking doesn't do much to yaw control. But it must've added quite a bit of drag in supersonic. I'm no pilot, but it seems you can turn by rolling with aileron and diff elevators without yaw input at all.

My understanding is that Mach tuck is something else. It is caused by shift of centre of lift of the main wing from quarterchord to midchord as the flow over the wing separates as it locally exceeds the speed of sound (it is like stall, but the post-stall lift is still plenty to keep the plane flying at this speed, so it is only the difference in centre of lift that matters).

… that of course does not mean shock wave from the bend between the fixed and movable surface is not a problem—it generates additional drag and reduces the effectiveness.

Anyway, I suspect the answer is that the rudder is mostly needed for cross-wind take-off and landing—when at low speed changing camber with separate rudder is better than changing angle of attack—while at high speeds the passive yaw stabilization is enough—and if the rudder is not deflected, there won't be a shock wave at the hinge.

Probably not used at high speed. On big airplanes rudder deflection is very limited at high speed as well.

There aren't a lot of yawing moments on a single engine jet like the Viper pictured, so you don't need much rudder.

you might want to look at the test and evaluation reports on the F-107. It used an all moving vertical stabiliser, maybe the documentation on it can shed some light on why it wasn't more widely adopted. Of course that's assuming that documentation is publicly available (or through a FOIA request).

Basically, in fighter aircraft you need a lot more of elevator than rudder.
For most aircraft, the required size of the elevator is determined by one of the two corner cases:

Sufficient control and balance at low speed, particularly on landing;
Sufficient control for high-G manoeuvres.

For fighters and aerobatic aircraft, the latter is usually the main factor; for others, the former.
In contrast, rudder is usually sized for crosswind landing and, if applicable, for the asymmetric thrust (one engine out) case. It's easy to see that due to closely packed engines on most fighters and higher speeds, both these factors are relatively smaller compared to other aircraft (e.g. airliners).(1) Whereas the elevator demand gets worse. This is why.
There are two main problems that arise at supersonic speeds.

The centre of pressure of the wing (and the neutral point) moves back significantly. This obviously creates a strong nose-down moment (and makes the aircraft statically very stable in pitch for the same CG), requiring a lot of control to re-trim the aircraft and execute any manoeuvre. This is the reason for 'Mach tuck' (in fact, this is the Mach tuck), and not the rubbish from the quoted Wikipedia passage.
Efficiency of the elevator fades. At lower subsonic speeds, the elevator effects the air not only above/below it, but also ahead of it. The approximate efficiency of the conventional elevator at such speeds can be expressed as
$$k_{\mathrm{elev}} = \sqrt{\frac{ S_{\mathrm{elev}}}{S_{\mathrm{stab}}}}$$
Therefore if the elevator $S_{\mathrm{elev}}$ occupies half of the stabiliser area $S_{\mathrm{stab}}$, its effect will be not $0.5$ but rather $\sqrt{0.5} \approx 0.7$ (compared to the all-moving surface). But at supersonic speeds such propagation upstream cannot happen, and the efficiency falls to the area ratio, i.e. $0.5$ in this example. This favous all-moving surfaces.

The second point affects the rudder just the same, of course. But the static directional stability (point 1) doesn't increase like it happens with pitch (in fact, it can fall), and the overall demand is lower, so conventional rudder is still acceptable. Nevertheless, there are a few aircraft with all-moving vertical tail, for example, Tu-160.
In other circumstances, conventional control surfaces are better (i.e. lighter), so they are used whenever possible.

(1) This should not be confused with the whole vertical tail sizing. This one is often determined by the stability dynamics, and directional stability of supersonic aircraft can be rather bad, demanding big tail - but not necessarily big rudder.


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Why do we lean the mixture in a turbocharged airplane (C182T)?
An increase in Altitude will result in a decrease of atmospheric pressure -1 in. Hg. / 1000ft (ISA conditions), but with a turbocharged airplane it will keep the pressure constant (+/- MSL pressure) up to the critical altitude? Why do we have to lean the mixture although pressure is kept constant or has it do with the fact that density decreases and thus reduce the amount of molecules for a given fuel molecule? What is the relationship between pressure and density? Thanks :-)

Turbo or not, you lean mostly because the mixture required for takeoff is far richer than necessary for lower power settings, even at sea level.  Aircraft engines are partly air cooled and partly liquid cooled - the full-time liquid cooling is oil, and on takeoff, there is part time liquid cooling in the form of excess gasoline from the full rich mixture.
The reduction in air pressure with altitude, or density with heat, means this effect becomes more extreme the higher you go, but you should be leaning, even at sea level, once power is reduced from takeoff (you should be leaning on the ground as well as soon as the engine is running smoothly after start, until just before takeoff, if you want to best mitigate the effects of the lead in the avgas).
The turbocharger just fools the engine into thinking its altitude is lower than it really is. A cruise power setting of 22" of manifold pressure is 22" inches of manifold pressure to the engine, whether it's 22" of natural atmospheric pressure achieved at wide open throttle at 8000 ft on a non-turbo engine, or 22" of artificially produced manifold pressure at 15000 ft in the turbocharged one.
The density of the compressed air intake charge is reduced by compression heating of the charge by the turbo, which reduces its efficiency (you'll need a slightly wider throttle opening to get the same MP with a hot charge) and complicates cooling (the hot air reduces detonation safety margins). Intake intercoolers are used to reduce the temperature of the intake charge, without reducing the pressure, to mitigate this problem.
In all cases, leaning is done in reference to exhaust gas temperature, usually some value on the lean side of peak EGT to get best fuel economy and relatively cool cylinders, with an eye on cylinder head temperatures.
With a turbo, the main effect of altitude that has to be kept in mind is cylinder cooling efficiency.  The turbo gives the engine an artificial ability to make low altitude power at high altitude. The problem is although the intake charge is "thick", being compressed air, the air coming in to cool the cylinders is "thin" and the heat rejection rate via the cooling fins declines, so leaning and cowl flap settings need to take this into account in managing cylinder head temperatures.
Exactly how that is to be done depends on the engine/airframe, per the POH and you should be leaning at all times based on POH procedures.
Cooling efficiency is critical to cylinder life with turbocharged engines, because they tend to operate a lot closer to temperature margins because of the demands of cooling in thin air. Good engine baffling is key.  Badly installed baffles or degraded baffle seals, that wouldn't be a problem in a non-turbo installation, can cause high cylinder head temperatures with a turbo at higher altitude.  Even if the cylinder head temperatures are good, bad baffles can lead to hot spots not picked up by the CHT probes and can ruin a cylinder with no obvious outward signs until it's too late.

most excellent answer!


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What is the best way to determine Run-in direction for parachute activity?
I am very new into flying skydivers. The aim is to get skydivers to a certain altitude usually 14000ft as quick as possible. They have to be dropped into a certain direction to compensate for wind. The correct direction of the run-in is vital so that the skydivers can reach the field they intend to land in. Are there any good tips / tools to determine the best run-in direction regarding winds aloft, especially when the wind changes during the day and wind shifts exist in the vertical profile? Thanks.

I used to skydive and was going to fly the jump plane but didn't have a commercial license at the time (required in Canada).  I was jumping at the dawn of the ram-air era in the late 70s. I had a lowly short-line Paracommander I bought second hand, because I couldn't afford a Strato Cloud ram air rig that was the must-have for most jumpers as soon as they got off training.  Good spotting was a lot more critical in the days of round parachutes, even for the Paracommander, that had a passable glide ratio of about 1:1.
The target location of your drop should be the upwind location the jumper wants to be, at opening altitude, roughly, passing 3000 ft, based on the winds between the surface and 3000 ft.  Once that geographical point is established, you want to find a heading that puts you along a track between the bowl and the exit spot, taking into account the winds at the drop altitude.
So in the end for you it is a simple pilotage navigation exercise.  You just need to look up the winds at exit altitude, and you simply estimate a heading to get yourself aligned on the bowl-to-drop-point track (established by the lower wind direction and velocity), and follow the jump master's directional corrections as they look straight down to observe the actual track, and cut when told as you get over the spot.
So if the winds aloft are say, due north at 14000 ft, and the bowl to spot track established by the wind speed and velocity below 3000 ft along the ground is 330 degrees and a mile upwind, I would work out the heading required to fly a 330 deg track based on the 14000 ft winds, say 345 or whatever, and start with that.
The other main issue is you need to plan your flying on the way up to get you to the drop altitude just as you are getting on to the final drop run track, (crossing the DZ or maybe just before) so you spend a minimum amount of time in level flight.  After the first couple of runs of the day you will have it pretty much worked out so minimal corrections are required during the run.


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Does the center of lift have to be in line with the center of mass?
Imagine 2 theoretical planes, A and B, shown in the image below. The center of mass is yellow, and the center of lift is blue. Would plane A and plane B work as well as an airplane with the center of lift in line with the center of mass or no?

As drawn, the rear center of lift and forward center of gravity will lead to a rapid nose-down pitching motion. Better to place both centers at the same lengthwise station.

I don't think it is intended to be to scale along the longitudinal axis, it is the different vertical position of the blue dot that is pertinent to the question.

Presumably "center of lift" is intended to mean "aerodynamic center" in this question. (Has someone been playing Kerbal Space Program? I had a "Yeager moment" in that game the other day when my spaceplane reentered the atmosphere in a bad attitude…)

In my opinion the vertical position of the center of gravity (CG) is negligible.
First of all the variation will be very small. Between an airplane with lead on the bottom of the cargo and an airplane with all passengers on the upper deck the CG will not move that much. And statistically the CG will probably be somewhat around the centerline of the fuselage.
Then, yes drag forces and engine thrust could create a tiny pitching moment but the leverage will only be a few inches at max thus the moment being very small compared to the gravity VS lift pitching moment resulting from the horizontal distance between CG and CP.
In the end question is somewhat similar to :
"what's better low or high wing planes?". On one side CG is above or near the wings and on the other hand way below the wing. Both works fine and requires only small design variations for aerodynamics stability.

You know vertical position of the CG is negligible since it is not evaluated.

What is missing from the diagram is the vectoral representation of the Center of Lift. Unlike the center of Mass, which is just a point within the aircraft. the Center of Lift or the Aerodynamic Center, is meaningless unless you also show the direction that the vector sum of all aerodynamic forces is acting in. You cannot know whether the Aerodynamic force is "in line" with the Center of Mass unless you know what direction the Aerodynamic forces are acting in.
For example, if the the vector sum of all aerodynamic forces is acting through the blue dot but pointing straight back, then it's extension will pass above or below the Yellow (CG) dot based on where the blue dot is vertically located. In both locations for the blue dot, if the aerodynamic force vector is oriented so that it passes THROUGH the yellow dot, there will be NO pitching moment, no matter where it is located vertically.
Since in most aircraft, the Aerodynamic center is behind the CG, and in normal straight and level flight, the vector must of course be pointed upwards and slightly aft (due to the drag component), the vertical position of the Center of Pressure will have only a minor impact on the static margin. The term "Static Margin" is often used to describe this phenomenon. It is a measure of the distance between the extension of the Aerodynamic force vector and the position of the center of Mass. The lower the static margin, (the closer the vector is to the CG), the less stable the aircraft is and the more the trim forces are required to keep it in balance.